1. Field of the Invention
The invention relates to electrical connectors. More specifically, the invention relates to electrical connectors with strain relief features.
2. Brief Description of Earlier Developments
Various types of electrical connectors rely upon surface mount technology (SMT) to secure the connector""s contacts to an underlying substrate. SMT connectors provide numerous benefits over earlier connectors, such as simplified manufacturing and lower costs.
While providing such advantages, the use of SMT may raise other issues. One concern, for example, involves the ability of the solder joint between the contact and the underlying substrate to absorb forces caused by, for example, shipping, handling, mating and thermal cycling. Should one solder joint become unusable as a result of damage from any of these events, the entire connector adversely may be affected.
Ball grid array (BGA) technology is one type of SMT. Generally, an electrical connector using a BGA has a housing with a contact therein. A fusible element, typically a solder ball, secures to each contact. The solder balls serve as the primary connection between the contact and the surface of the substrate. A reflow process fuses the solder ball to the substrate. During the reflow process, a beneficial xe2x80x9cself-centeringxe2x80x9d feature of the BGA technology occurs. Specifically, as the solder reflows, the surface tension of the solder helps to align the connector properly with the conductive pads on the underlying substrate.
As with SMT connectors, forces on the solder joint in a BGA connector also poses a concern. Because of the self-centering ability of BGA connectors, however, many of the solutions used in SMT connectors cannot be used on BGA connectors. Therefore, a need exists to develop techniques for providing strain relief to BGA connectors.
It is an object of the invention to provide an electrical connector with strain relief features.
It is a further object of the invention to provide a surface mounted electrical connector with strain relief features.
It is a further object of the invention to provide a ball grid array electrical connector with strain relief features.
It is a further object of the invention to provide strain relief features to a ball grid array electrical connector compatible with the self-centering capability of the connector.
It is a further object of the invention to provide an electrical connector made with simplified manufacturing steps.
These and other objects of the invention are achieved in one aspect of the invention by an electrical connector mountable to a substrate. The electrical connector comprises a housing, and a surface mount contact and hold down both secured to the housing. The hold down may be a surface mount hold down. The connector may further comprise a shield generally surrounding the housing, wherein the hold down is part of the shield. The surface mount contact may include a fusible element in the form of a solder ball. The surface mount contacts may form a matrix array. Also, the electrical connector may be constructed such that it remains substantially parallel when mounted to the substrate. The electrical connector may include a standoff secured to the housing, wherein the standoff is adapted to retain the housing a distance from a surface of the substrate. The standoff may be a part of the shield.
These and other objects of the invention are achieved in one aspect of the invention by a ball grid array connector comprising a housing, a plurality of contacts within the housing, a plurality of fusible elements secured to the contacts for mounting the connector to a substrate, and a hold down secured to the housing. The hold down may be a surface mount hold down. The ball grid array connector may further comprise a shield generally surrounding the housing, wherein the hold down is part of the shield. Also, the ball grid array connector may include a standoff extending from the housing and adapted to retain the housing a distance from a surface of the substrate. The standoff may be a part of the shield. The ball grid array connector may be constructed such that it remains substantially parallel when mounted to the substrate.
These and other objects of the invention are achieved in one aspect of the invention by a method of mounting an electrical connector to a substrate. The method comprises providing a substrate and an electrical connector having a contact and a hold down, and securing the contact and the hold down to the substrate. The contact may be secured to a surface of the substrate. The contact may be secured before the hold down is secured, using a soldering technique, for example, to permit the connector to self-center on the substrate. The electrical connector may include a shield that is secured to the substrate. The method may further comprise constructing the electrical connector such that it remains substantially parallel when mounted to the substrate. Also, the method may comprise balancing the electrical connector on the substrate such that the electrical connector remains substantially parallel to the substrate during they are attached. The electrical connector may be a ball grid array connector.
These and other objects of the invention are achieved in one aspect of the invention by a method of securing an electrical connector to a substrate. The method comprises providing a substrate and an electrical connector having a contact and a hold down, and mounting the contact to the substrate. The method further comprises balancing the electrical connector on the substrate such that the electrical connector remains substantially parallel to the substrate during the forming of the first and second solder joints. Such balancing may be accomplished by removing material from and/or adding material to the electrical connector. Alternatively, the balancing may be accomplished by exerting an external force on the electrical connector and/or the substrate during the forming of the first and second solder joints.
These and other objects of the invention are achieved in one aspect of the invention by an improved array connector having a plurality of fusible elements that are able to support a nominal mass without an undesired flattening of the fusible elements. The nominal mass is less than a mass of the connector. The improvement comprises a feature on the connector that prevents the undesired flattening of the fusible elements. The feature may comprise a standoff. Alternatively, the feature may comprise an area of material removed from a housing of the connector.
These and other objects of the invention are achieved in one aspect of the invention by an improved electrical connector mountable to a substrate, having an array of fusible elements, and exhibiting an unbalance relative to the fusible elements. The improvement comprises a feature on the connector that prevents the unbalance from causing an undesired skewing of the connector when mounting the connector to the substrate. The feature may comprise a standoff. Alternatively, the feature may comprise an area of material removed from a housing of the connector.